Voice Dialing won't work on Virgin Aloha - in "Talk Button" mode

I have a brand new Aloha phone from Virgin. I have set it up for voice
dialing, and it works OK if I put it in the "flip open" mode - to accept
voice dial commands when I unfold the phone. But my preference would be
to voice dial in the "talk button" mode - giving commands after
pressing the green talk button. That does not work - it just displays a
list of recently dialed calls - and the helpful people at Virgin's phone
bank can't figure out why.

Any suggestions?

Ham